Annunciator system having acknowledgment and using gaseous triodes



J'an. 12,1965. 5;

ANNUNCIATOR SYSTEM HAVING ACKNOWLEDGMENT. AND USING GASEOUS TRIODES FiledlJan; 5., 1962,

2 Sheets-Sheet 1 INVENTOR.

EDWARD 5. !DA BY ATTORNEY- Jan; 12', 1965 5, 5115 3,165,724

ANNUNCIA-TDUR SYSTEM HAVING' ACKNOWLEDGMENT AND USING; GASEOUS TRIOD'EES-A Filed Jan. 5', 1952 2 Sheets-Sheet 2 FIG.3

INVENTOR.

EDWARD S. IDA

ATTORNEY United States Patent 3,155,724 ANNUNCIATGR SYSTEM HAVING ACKYO'WL- EDGMENT AND USING GASEQUS TRHGDES Edward S. Ida, Folsom, Pa., assignor to E. I. du Pont de Nernours and Company, Wilmington, Del., 2 corporation of Delaware Filed Jan. 5, 1962, Ser. No. 164,496 7 Claims. (Cl. 340213.2)

This invention relates to an improved electrical annunciator, and particularly to an annunciator adapted to signal momentary alarm conditions as well as those of sustained duration.

This application is a continuation-in-part of my copending application S.N. 16,775, filed March 22, 1960, now issued as US. Patent 3,076,185, directed to a transistorized annunciator, and, in some respects, this invention is an improvement thereon.

The steadily increasing complexity of manufacturing operations necessitates more or less continuous surveillance concurrently or" a multiplicity of operating conditions. This has led to a proliferation of independent sensing circuits each of which is adapted to monitor, or in some instances directly elfect, a specific process step. It is imperative that there be positive assurance at all times as to the moment-by-moment status of each individual operating condition as sensed by the associated monitor circuits, which often total hundreds or even thousands of points, as the individual circuits are customarily called. Annunciator circuits fulfill the need of checking the operation of single points. It will be appreciated that simplicity of design of these annunciators is of prime importance, since even low cost units aggregate to very large sums when a great number of points must be serviced. At least of equal importance is the provision of high reliability in the annunciators, because absolute trust must be placed on the devices for the instant ascertainment of the operational status of the entire manufacturing establishment.

An object of this invention is to provide a low cost annunciator using few parts, and these of extremely high proven reliability. Another object is to provide an annunciator capable of detecting the existence of momentary alarm conditions, as well as those of relatively sustained duration. Other objects of this invention include the provision of an annunciator adapted to employment with certain very desirable auxiliaries, such as, for example, a first-on indicator and a ring-back indicator, both of which designs dispense with relays and other like devices capable of generating appreciable electrical interference. The manner in which these and other objects of this invention are attained will become apparent from the detailed description and the following drawings, in which:

FIG. 1 is a schematic circuit diagram showing a.

preferred embodiment of annunciator according to this invention represented in association with a rnulti-point serving audible alarm adjunct, together with a multipoint first-on alarm indicator auxiliary,

FIG. 2 is a schematic circuit diagram showing a modification of circuit applicable to FIG. 1 required for the incorporation of a ring-back auxiliary indicative of restoration of the point to normal service following correction of the underlying cause for failure occasioning the alarm in the first instance, and

FIG. 3 is a schematic circuit diagram showing an alternate lamp circuit utilizing an A.-C. power source which is characterized by low power dissipation at all illumination levels and, therefore, is preferred in situations where power economy is especially desired.

Generally, this annunciator comprises in combination 3,155,724 Patented Jan. 12, 1%55 an alarm lamp connected across an illuminating power source in series. with a voltage-limiting element pre selected to operate the lamp at a first characteristic level of illumination below full brilliance, a transistor connected with collector and emitter elements in series with the filament of the alarm lamp and in parallel with the voltage-limiting element through a biasing diode to the positive side of a D.-C. power source and with base element connected via the positive side of a first diode intermediate (1) a flasher signal apparatus provided with a second diode and (2) a gaseous triode, which devices (1) and (2) are connected in series with a first acknowledgement switch contact pair as a first network connected across the D.-C. power source, an alarm switch contact pair connected in series with resistors on both positive and negative sides of the alarm switch contact pair as a second network in parallel with the first network across the D.-C. power source, and coupling means firing the gaseous triode responsive to the opening of the alarm switch contacts connected in electrical circuit between a point within the second network on the positive side of the alarm switch contact pair and the grid of the gaseous triode.

Referring to FIG. 1, a preferred embodiment of this invention, in which the illuminating power is D.-C., utilizes an alarm indication lamp 10, which can be a v., 6 watt type, connected to the 120 V. DC. bus 11 and, by positive power supply lead, to ground 12 through a voltage-limiting element which, in this case, is series dimming resistor 14. Connected in parallel to resistor 14 is a P-N-P transistor 15 (typically an RCA type 2N586) having its collector and emitter elements in series with the filament of lamp 10 through a Zener diode 16 via lead 19 biasing the emitter at about 5 v. The base element of transistor 15 is connected via the positive side of a diode 17 (typically, type 1Nl692) to a point intermediate a flasher apparatus, denoted generally at 13, together with its associated diode 20 and currentlimiung resistor 21, and gaseous triode 22 (in this case an LTG272 neon triode) provided with its own currentlimiting resistor 23 (typically 27K, w,, 10%). Flasher apparatus 18, not detailed in circuit, is of conventional design shown in the GE. Transistor Manual, 2nd edition, page 90, delivering a modulated current flow of 0-1.5 ma. to transistor 15 at a frequency of about 1 cycle per second. Diode 20 isolates the flasher so that one unit can be made to serve a multiplicity of annunciators.

H The circuit of triode 22 is completed to power bus 11 by the connection including a first pair of normally closed acknowledgment switch contacts denoted 28.

The balance of the basic annunciator circuit of this invention is completed by the connection in shunt with respect to the two sub-circuits hereinbefore described of normally closed alarm contact pair 30 through series resistors 31 and 32 (each typically, 27K, A w., 5%) to the power source. As coupling means a 0.05 mfd. capacitor 33 is connected between the positive side of switch contacts 30 and resistor 31 on the one hand and the grid of triode 22 on the other as the operation-inducing agency of the annunicator, while a diode 44 is connected in shunt with respect to switch contacts 30 between the grid of gaseous triode 22 and the negative side of switch contacts 30.

The apparatus in the form so far described is completely operable as an annunciator; however, the acknowledgment function is provided by connecting a second gaseous triode 36, which can be a neon triode of type identical with triode 22, in shunt around alarm contact pair 30 through a voltage-dropping resistor 37 (typically, 27K, W., 10%) and with tap connection at 38 intermediate the base of transistor 15 and diode 17. The grid of triode as 'follows.

button operation concurrently with contacts 28, to bus 11 by a lead 40 provided with resistors 41 and 42 (each I typically 120K, w., 10% type), and the latter of which is connected to ground at 43.

The operation of the basic annunciator described is With alarm contacts 3t) closed, as is normally the case, and with triodes 22 and 36 extinguished, transistor 15 will be non-conducting, due to its -5 v. reverse bias, and lamp will be illuminated dimly due to the voltage drop across itsseries resistor 14. Upon failure occurring within the apparatus monitored by the annunciator circuit, alarm contacts 30 are made to open by conventional means not detailed herein, whereupon capacitor 33 coupled to the grid of triode'22 causes the latter to fire. The repetitive opening and closing of the flasher circuit 18 contacts responsive to flow of current through triode 22 causes a modulation of current how to transistor between-0 and 1.5 ma. at a typical frequency of 1 cycle per second, the voltagedrop across triode 22 remaining constant at approximately 80 volts. The current flowing to the base of transistor 15 is amplified at a current gain, of typically 75 to cause lamp 10 to flash .from dim to bright repetitively, thereby signaling an alarm condition.

Should alarm contacts 30 reclose, triode 22 remains lit, continuing the visible signal of lamp 10. In this connection, diode 44 is provided as a safeguard against the accidental extinguishment of triode 22.

Depressing the acknowledgment button, and thereby opening contacts 39, ignites the second triode 36, which permits passage of a steady current to transistor 15 driving it to full conduction with maintenance of lamp 10in steady bright illumination at a current consumption of about 50 ma. Diode 17 prevents the diversion of current from triode 36 through flasher 18 to ground. Supplying excess driving current to transistor 15 assures its operation as a'switch, with minimization ofits power dissipation and consequenet heating.

Coincidentally, the power supplyto triode 22 having been interrupted by the opening of contacts 28, triode 22 is, during this time, extinguished, capacitor 33 permitting this to occur even when alarm contacts 3% remain open.

Lamp 10' remains illuminated at steady bright until alarm contacts 30 reclose, reducing the voltage to triode 36 below the level maintaining glow discharge, Thereupon, triode 36 is extinguished and lamp 10 immediately I reverts to its dim, cycle.

It is often desirable to provide, in addition, an audible alarm signal, and this is readily done by the inclusion of a horn 48together with its necessary auxiliaries, such as or normal condition, completing the conventional audio oscillator 49 and power amplifier 5d,-

a single horn servicing a number of points, typically fifty or more in number, on a shared basis. Thus, each individual point is provided with a diode 51, 51a, 5112,

etc. (typically, 1Nl692 or HBS types) together with a voltage-droppingresistor 52 (shown for the single annunciator circuit elaborated solely), with the circuit to the base of transistor 53 (typically, an RCA type 2N5S6) being completed through lead 54 and to ground through resistor 55 (typically, 150K, A w., 10%). The power supply from bus 11 is provided to both audio oscillator 49and power amplifier 56 in parallel via zener diode Sd (typically, 100 v. size) and zener diode 16, previously described (typically, 5 v. size). In operation, the same sequence of events which operates triode 22 is effective to concurrently send the necessary actuation signal totransistor 53, which thereupon provides amplification actuating oscillator wand sounding horn 48 through the intermediate amplification of St).

A very desirable auxiliary, particularly in the case of momentary apparatus failures in which the sequence of failure is significant, is a first-on indicator, a preferred nected to the output end of resistor 52' .nected ,to the anodeside of triode 36'.

design of which is the subject matter of US. application SLN..168,438, filed of even date herewitl1( now US. Patent 3,113,299). This utilizes a multiplicity of "gaseous triodes (typically, LTG 27-2 neon types) each of which is reserved'to an individual point. Thus, in FIG. 1, triode 60 is reserved for the annunciator elaborated in detail, connection therewith being made via resistor 61 direct to the grid, with cross connection to the anode via diodes 52 and 63 (each typically 1N1692 type). Similarly, individual other points are connected to their reserved triod 69a, 6012, etc., via resistors 61a, 61b, etc., respectively, with the diodes of like function denoted 62a, 62b, etc., and 63a, 6312, etc. 'All of the anodes are connected to one another across the diode 63, 63a, 63b, etc., via lead 64, connected through voltage-dropping resistor 66 (typically, K, A w. size) to ground, and each triode is provided with a voltage-dropping resistor 65,

65a, 65b,-etc. (typically, 39K, A w. size), respectively, connected to ground. Finally, all of the cathode elements of triodes 60, 60a, 60b, etc., are connected direct to bus 11, a common pushbutton switch 67 (normally closed) being provided for acknowledgment and restoration to ready condition of the first-on auxiliary as desired.

As a convenience in interpretation, all triodes 60, 60a, 6022, etc., are preferably mounted in labelled array in' a common bank, and the individual illuminations of the triodes per se relied upon as the signal manifestations. All of the triodes are initially non-conducting, and remain so as long as the associated alarm contacts 30 remain closed. However, the first alarm input incident to the opening of a contact pair 30 causes the corresponding triode to fire. The voltage developed across the associated voltage-dropping resistor 65, 65a, 65b, etc., as the case may be, causes the associated lower diode 63, 63a, 6317, etc., to conduct, which in turn causes all of the remaining upper diodes 62, 62a, 62b, etc., to clamp their associated grids to a potential approximately midway between 0 and 1'2() volts. Under these circumstances, sufficient voltage is prevented from being developed by subsequent inputsignals originating at other points to fire any of the other triodes. Thus, the first point to alarm is eflectively remembered until the acknowledgement switch button 67 is opened to clear the circuit and then'reclosed to restore -it to the ready condition again.

are indicated by the same reference numerals with a prime appended, and it will be seen that only very minor circuit alterations are required 'to the basic circuit hereinbefore described in order to accommodate the ring back auxiliary. These primarily consist of the substitution of a resistor 70 for capacitor 33 in circuit with the grid of triode 22, elimination of diode 44, and the incorporation of a transistor 71 (typically, a 2N586 type) with emitter connected to the base of transistor 15, collectorconand base con- In addition, since the tap connection from. triode'36' to the base of transistor 15' is now eliminated, it is necessary to provide anew resistor 72 (typically, 27K) from this element to ground. I v

The purpose of the ringback circuit of FIG. 2 is to call the operators attention to a return to normal condi- 'tion of the monitored point. The operation of; the annuciator is completely 'as hereinbefore" described with reference to FIG. 1, except'that triode 22" is'not now ex-, tinguished when the acknowledgement button is pressed, or released, as long as alarm contacts 36' remain open, since a resistor, i.e., 75, has nowbeen substituted for the previously described capacitor 33. The second triode 36 is fired normally and its current causes transistors 71 and 15' in circuit therewith to switch to a continuously conducting state. The audible signal is thus diverted to. ground and silenced.

When alarm contacts 30' return to normal, i.e., close, the acknowledge triode 36' is again extinguished, and transistor 71 returns to non-conducting state. However, since the first triode 22 is not thereby extinguished, lamp again flashes and the audible signal sounds, in this manner providing the ringback signal which is the auxiliary circuits function. If the acknowledgment button is again depressed, triode 22' will extinguish and the entire circuit is once again restored to normal state in condition for repetition of the cycle should circumstances require.

It is entirely feasible to utilize an A.-C. illuminating power source in this invention, and a modified sub-circuit for such purpose is shown in FIG. 3, wherein elements in all respects identical to those of FIG. 1 are indicated by the same reference numerals with a prime appended.

In this case the power source is a transformer (typi cally, a 4:1 ratio, step-down type, such as a Stancor RTZOI), indicated generally at 75, having its 28 v. secondary in series with the filament of lamp 10'. The circuit is completed back to the transformer secondary by a voltage-limiting element comprising diode 76 (typically 1N1692 type), which efiectively conducts only onehalf the power received from the transformer, and thereby maintains lamp 10 in its dimly illuminated state until transistor in parallel with diode 76, operates as hereinbefore described for the circuit of FIG. 1, whereupon lamp 10 flashes to bright. Bias on the emitter of transistor 15 is maintained at about 5 v. by connection with lead 19 running to a zener diode (not shown) in all respects identical with zener diode 16 of FIG. 1.

The power circuit of FIG. 3 is particularly adapted to use with smaller lamps such as the 70 13121., 2 w. type, or, indeed, with higher power lamps, subject to supply of sufiicient transistor driving current, and, of course, has an extremely low power dissipation, which can be an important advantage where a great number of annunciator units are involved.

It is preferred to incorporate a normally closed, springreturned test switch 77 in series with alarm contacts 30 and resistors 31 and 32 across the power source, so that the operative state of the annunciator circuit can be immediately verified at any time, independent of the existence of a process deviation, by momentarily opening the test switch and observing the resulting annunciator operation or non-operation, as the case may be. As an economy measure, it will be understood that test switch 77 can be connected in series electrical circuit with a plurality of individual alarm contacts 30 and their associated resistors, so that an entire block of, typically, twenty or more annunciators can be tested simultaneousl Fi om the foregoing it will be understood that this invention can be modified in numerous respects without departure from its essential spirit, and it is therefore intended to be limited only within the scope of the following claims.

I claim:

1. An annunciator circuit comprising in combination an alarm lamp connected across an illuminating power source in series with a voltage-limiting element preselected to operate said lamp at a first characteristic level of illumination below full brilliance, a transistor connected with collector and emitter elements in series with the filament of said alarm lamp and in parallel with said voltage-lim switch contact pair connected in series with resistors on both positive and negative sides of said alarm switch contact pair as a second network in parallel with said first network across said D.C. power source, and coupling means firing said gaseous triode responsive to the opening of said alarm switch contacts connected in electrical circuit between a point within said second network on the positive side of said alarm switch contact pair and the grid of said gaseous triode.

2. An annunciator circuit according to claim 1 wherein said illuminating power source is of the alternating current type and said voltage-limiting element is a diode.

3. An annunciator circuit according to claim 1 wherein said coupling means consists of a resistor.

4. An annunciator circuit according to claim 1 wherein there is provided a second gaseous triode connected with said power source in shunt circuit around said alarm contact pair with tap connection on the positive side of said second gaseous triode within said last-mentioned shunt circuit to a point between said positive side of said first diode and said base element of said transistor, said second gaseous triode having its grid connected in series through a second acknowledgment switch contact pair ganged for con-.

current switching operation with said first acknowledgment switch contact pair to the negative side of said D.C. power source.

5. An annunciator circuit comprising in combination an alarm lamp connected across a D.C. illuminating power source in series with a voltage-limiting resistor preselected to operate said lamp at a first characteristic level of illumination below full brilliance, a transistor connected with collector and emitter elements in series with the filament of said alarm lamp and in parallel with said voltage-limiting resistor through a biasing diode to the positive side of said power source and with base element connected via the positive side of a first diode intermediate (1) a flasher signal apparatus provided on its output side with a second diode and (2) a gaseous triode, which devices 1) and (2) are connected in series with a first acknowledgement switch contact pair as a first network connected across said power source, a normally closed alarm switch contact pair connected in series with resistors on both positive and negative sides of said alarm switch contact pair as a second network in parallel with said first network across said power source, and coupling means firing said gaseous triode responsive to the opening of said alarm switch contacts connected in electrical circuit between a point within said second network on the positive side of said alarm switch contact pair and the grid of said gaseous triode.

6. An annunciator circuit comprising in combination an alarm lamp connected across an illuminating power source in series with a voltage-limiting element preselected to operate said lamp at first characteristic level of illumination below full brilliance, a transistor connected with collector and emitter elements in series with the filament of said alarm lamp and in parallel with said voltage-limiting element through a biasing diode to the positive side of a D.C. power source and with base element connected via the positive side of a first diode intermediate 1) a flasher signal apparatus provided on its output side with a second diode and (2) a gaseous triode, which devices (1) and (2) are connected in series with a first acknowledgment switch contact pair as a first network connected across said D.C. power source, a normally closed alarm switch contact pair connected in series with resistors on both positive and negative sides of said alarm switch contact pair as a second network in parallel with said first network across said D.-C. power source, and coupling means firing said gaseous triode responsive to the opening of said alarm switch contacts consisting of a capacitor connected in electrical circuit between a point within said second network on the positive side of said alarm switch contact pair and the grid of said gaseous triode, said capacitor being provided with a diode connected in shunt with respect to said alarm switch contact pair between the grid of said gaseous triode and the negative side of said alarm switch contact pair. I j

7. An annunciator circuit according to claim 6 Wh616i11 there is provided a second gaseous triode connected with said power source in shunt circuit around said alarm contact pair with tap connection on the positive side of said second gaseous triode within said last-mentioned shunt circuit to a point between said positive side of said first diode and said base element of said transistor, said second gaseous triode having its grid connected in series through a 10 2,840,804

second acknowledgment'switch contact pair ganged for concurrent switching operationwith said first acknowlcdgment switch contact pair to the negative side of said D.-C-. power source. 7

References Cited inthe file of this patent UNITED STATES PATENTS Faulkner '-Dec. 17, 1957 Rodgers June 24, 1958 

1. AN ANNUNCIATOR CIRCUIT COMPRISING IN COMBINATION AN ALARM LAMP CONNECTED ACROSS AN ILLUMINATING POWER SOURCE IN SERIES WITH A VOLTAGE-LIMITING ELEMENT PRESELECTED TO OPERATE SAID LAMP AT A FIRST CHARACTERISTIC LEVEL OF ILLUMINATION BELOW FULL BRILLANCE, A TRANSISTOR CONNECTED WITH COLLECTOR AND EMITTER ELEMENTS IN SERIES WITH THE FILAMENT OF SAID LAMP AND IN PARALLEL WITH SAID VOLTAGE-LIMITING ELEMENT THROUGH A BIASING DIODE TO THE POSITIVE SIDE OF A D.C. POWER SOURCE AND WITH BASE ELEMENT CONNECTED VIA THE POSITIVE SIDE OF A FIRST DIODE INTERMEDIATE (1) A FLASHER SIGNAL APPARATUS PROVIDED ON ITS OUTPUT SIDE WITH A SECOND DIODE AND (2) A GASEOUSE TRIODE, WHICH DEVICES (1) AND (2) A GASEOUSE TRIODE, WHICH DEVICES EDGMENT SWITCH CONTACT PAIR AS A FIRST NETWORK CONNECTED ACROSS SAID D.-C. POWER SOURCE, A NORMALLY CLOSED ALARM SWITCH CONTACT PAIR CONNECTED IN SERIES WITH RESISTORS ON BOTH POSITIVE AND NEGATIVE SIDES OF SAID ALARM SWITCH CONTACT PAIR AS A SECOND NETWORK IN PARALLEL WITH SAID FIRST NETWORK ACROSS SAID D.-C. POWER SOURCE, AND COUPLING MEANS FIRING SAID GASEOUS TRIODE RESPONSIVE TO THE OPENING OF SAID ALARM SWITCH CONTACTS CONNECTED IN ELECTRICAL CIRCUIT BETWEEN A POINT WITHIN SAID SECOND NETWORK ON THE POSITIVE SIDE OF SAID ALARM SWITCH CONTACT PAIR AND THE GRID OF SAID GASEOUS TRIODE. 